


Cecalidae

by Bloomquist



Category: Gravity Falls
Genre: Drug-Induced Sex, M/M, Non-Consensual Drug Use, Octo!Bill, Sahir&Diabo, Tentacles, Underwater Sex
Language: English
Status: Completed
Published: 2017-09-26
Updated: 2017-09-26
Packaged: 2019-01-05 16:12:33
Rating: Explicit
Warnings: Major Character Death, Rape/Non-Con
Chapters: 1
Words: 1,411
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12193281
Author URL: https://archiveofourown.org/users/Bloomquist/pseuds/Bloomquist
Summary: Dipper dives into the sea to find a miracle from none other than Bill Cipher. Little does he know there's no hope.(Billdip Week Day 1: Creature AU)





	Cecalidae

The water was clear in this part of the sea. Dipper could see nearly a mile in every direction as he descended. This was where Bill Cipher had been pinpointed according to Ford - Who’d cross-referenced GPS of the ships and people that had gone missing, sea activity, and ocean floor contour maps. There were only two places where he could be hiding down here.

As Dipper descended, the ocean grew hazier and less populated. He felt the pressure against his helmet and adjusted his airflow, hoping the gear (and himself) would stand up to it. His feet hit the ocean floor with a thump and a sigh rattled from his lungs.

“Let’s do this.” he murmured into his helmet and trekked toward the cave jutting from the ocean floor ahead of him.

It didn’t take long for Bill to take notice of him - Or at least he assumed it didn’t when he was accosted within minutes. The cecalian form descended upon him in a whirl of bubbles, a flourish entirely unique to Bill’s personality.

“Well, if it isn’t Dipper Pines! One of you, anyway. Nice of you to drop in!”

Dipper stopped, attempting to make himself as little as possible. No fear, he told himself. No talking circles. He didn’t have time.

“I want to make a deal!” he called back, clenching his fists in their rubbery confines.

“In other news, the sun shines!” Bill replied, throwing his hands up toward the rays shining through the water. He shifted again out of Dipper’s limited range of view.

Sensing he was losing his grip on the conversation, Dipper tried hard to wrangle it back. “It-It's Mabel,” he stuttered, “I need your help, she’s going to die-”

“I’m not interested in Star, Pine Tree. Humans die all the time! Honestly, the way you all react is hilarious.”

The smell of desperation wafted through the water. Bill twirled the boy to face him with a jerk of a tentacle, and the expression on his face would have been enough to sway him if he had been anyone else.

“You don’t understand! I can give you your freedom again. Bill, please, I need...”

The water around them darkened perceptibly, blacking out the filtered sunlight above them. Dipper could no longer see the tiny hull of the boat above them. Bill visibly flared, all three golden eyes focused on him in a way that forced him to make a decision: Fight or flee.

As soon as he chose the latter, tentacles were on him like lightning. Dipper struggled vaguely in the water, but he had no method of escape. No flippers or fins to maneuver, no gills to save him if his helmet sustained damage. He realized rapidly that he had been a sitting duck waiting to be caught, and he’d invited death much too easily.

“You think you have anything I want? You’ve gotta be pulling my leg.” echoed Bill’s voice. He could no longer tell where exactly it was coming from.

Limbs encircled his legs and arms and slithered their way up his torso, debasing all hope. They began to pull away, bringing with them the tears and shreds of his wetsuit, sloughing off and drifting to the bottom like an extra skin - And in a way, it was one. The only thing protecting him from the way the tentacles suckered back up his bare limbs, making him thrash yet again to no avail.

The only thing he managed to do was jostle his helmet’s air supply. An ominous amount of bubbles floated toward the surface, and Dipper panicked worse for a moment until he froze at the sight of Bill’s still enraged face just above him. It vanished just as soon as it appeared, leaving him in the ink’s darkness.

“Careful, kid. Don’t want to lose anything important.” tittered the voice from another unknown location.

“Oh god,” Dipper whined from his confines. The tentacles took advantage of his compliance and tightened around his hips in a way that was all too-

Another appendage slipped up between his legs and oh, it was definitely what he was thinking. A less panicked gasp escaped his mouth and he rocked away from the sensation, but the tentacles held him fast. 

This time, the voice was close, much too close. “Ah, ah, ah,” it crooned, and the tone took on one of warning: Much more struggling and Dipper suspected he’d be dying all too soon. He fell limp in Bill’s grip, relaxing as well as he could to communicate his compliance. “Good boy. You were always smarter than I gave you credit for!”

Despite the praise, the limbs still found their way around him snugly, making him gasp for breath with the way they tightened around his diaphragm and thighs. He struggled to stay still as one of the appendages again slipped across the most intimate part of him, only jerking slightly when it pressed up against his entrance. “Stop,” he requested, but instead it pressed more insistently. After a moderate amount of pressure, the slick tip breached him unprepared, slipping in a couple of narrow inches and retreating just as fast only to repeat the process.

“Sto-” Dipper requested again, but the Bill appeared again, hands clamped tightly against both sides of his helmet. “Pine Tree,” he hissed back, “Be a good boy and enjoy yourself! I’m being nice.”

Before Dipper had the chance to ask how exactly this entailed nice the tentacle slid inside him and kept going, penetrating him to his limit. He released an anguished cry and tried to flail himself away, but didn’t manage to loosen a single sucker. “Sto-ah, please-” he begged, but the tentacle pushed onward and then withdrew, repeating the process with at first excruciating then ebbing pain. 

And then to his horror and Bill’s pleasure, an unfamiliar fever began to take hold of him. The heat spread from his chest and outwards to his limbs, causing him to arch and squirm for entirely different reasons. He moaned as the uncomfortable feeling of suckers turned into a fire that lit up his entire body. His lips numbed with the pleasure, and he bit down on them to bring the feeling back to no avail.

Instead of gloating this time, however, Bill only grinned darkly and vanished into the cloud again. A second tentacle slid up Dipper’s perineum and up his now hard length, suckering to it tightly in a corkscrew. He moaned openly at the contact and thrust his hips blindly forward, and was rewarded with a sharp suck. Oh god.

“Fuck, Bill!” he groaned, but there was no sign of the demon beside the tight grip he had on him beyond his vision. He closed his eyes against the darkness and moved experimentally, rolling his hips into the sensation that was invading his body and mind. He was rewarded by the quick tightening of his binds and he roiled in the feeling, throwing his head back as best as he could. Everything was bliss, he could feel it all - Every tightening grip and even his own short gasping breaths.

The moment he thought it would end as quickly as it began, however, the tentacle that had made its home around his erection tightened painfully. The pleasure, pure and unadulterated (god, when had it become that), crested violently and hung Dipper at the peak by a thread, and the pain of being unable to come brought a scream to his lips.

A tentacle snaked and shoved into his helmet, taking advantage of his open mouth. Soon his scream was silenced too and he was simply forced to endure, sensations and nerves grinding together and overwhelming too much too much- It went on for seconds, minutes, he didn’t know he didn’t care-

The grip finally released and he came hard, mind whiting out at the intensity. He couldn’t remember ever feeling quite like this; like his entire body was numb with the force of it. Every part of him went limp as it ebbed, leaving him in a haze, unable to utter a single word anymore. 

“Sahir,” a deep voice spoke from around him. He could no longer pinpoint voices period. He could no longer pinpoint where his own arms and legs were. He could barely pinpoint the extra pair of eyes in the darkness, glowing the same gold as Bill’s through the clearing ink. “A Dipper?”

A laugh escaped from behind him. Beside? It didn’t seem to matter.

“Dinner.”


End file.
